Press roll with adjustable flexion

Details Press roll with adjustable flexion Press roll with adjustable flexion

1982-02-22

1983-11-15

Feldman, Peter

Presses

Concurrent pressing and conveying

Roll type

29115, 29116AD, B30B 304

Patent

active

044148909

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION



Technical Field

The invention concerns a press roll with adjustable flexion, preferably intended for use in the paper industry. The press roll has a hollow shell that can rotate around a fixed yoke and, in conjunction with a mating roll, form a web, e.g. press nip for a web of paper, to travel through. The axis of rotation of both rolls lie in the same press plane as the press nip. The press roll has the following additional characteristics: away from the yoke. transfers support forces from the yoke to the shell along the press plane. areas of the yoke (the planes being perpendicular to the axis of rotation of the rolls,) is no longer than and preferably just as long as the distance between the mating-roll bearings.


State of the art

Press rolls of the type just described and similar rolls are known from the publications 3,932,921, 3,949,455, 4,213,232.
The shell of the press rolls known from Publications 1 and 2 is approximately as long as that of the mating roll and each end of the shell is mounted directly against the yoke with a self-aligning bearing. Thus the longitudinal distance between the center planes of the self-aligning bearings of the shell, said planes being perpendicular to the axis of rotation of the rolls, is shorter than the distance between the mating-roll bearings.
The press roll known from Publication 1 (especially FIG. 1, p. 169) is of the type called a floating roll. The hydraulic support is a semiannular pressurized compartment between the yoke and the shell extending essentially the total length of the shell. The roll known from Publication 2 on the other hand has a certain number of hydrostatic pressure shoes distributed along the press gap over the total length of the shell of the roll.
Rolls of this type are used to extract water in the wet sections of papermaking machines or to calender the dry paper, for example. The last function, especially, requires an especially precise nip between press roll and mating roll to maintain uniform paper thickness over the total width of the web. This is to ensure that the finished roll of paper will be as cylindrical as possible. If the two rolls do not mate precisely, the rolls of paper will be irregular in shape, making them hard to handle and leading to rejection.
When a web of paper is processed in a press of this type, the possibility of applying different pressures on the edges and on the middle of the web may also be desirable. This is done in an attempt to eliminate any irregularities in paper thickness produced in other sections of the paper machine, like variations in weight per unit areas or basis weight produced in the wet section, variations in the moisture of a felt, or variations in dryness over the width of the web upstream of a calender stack. One disadvantage of the known roll presses, which employ a press roll with adjustable flexion in conjunction with a solid mating roll, is that they frequently make it impossible to obtain the desired uniformly thick web. Deviations that vary with the level of pressure and that are apparently due to the distance between the mating-roll bearings being greater than the length of the press-roll shell always occur.
This disadvantage affects all known types, both the floating rolls known from FIG. 1, page 169 of Publication 1 and the rolls known from Publication 2.
Using a correction compartment and what are called ring elements, which have no internal pressure, to correct irregularities in web thickness is admittedly known from Publication 1. Still, since the design of the roll press remains unaltered in principle, it has been impossible up to now to eliminate the basic causes of such irregularities.
Another type of press roll is disclosed in Publications 3 and 4, in which the shell is provided with an extension at each end, with the shell bearings mounted on the extensions. The result is a greater distance between the bearings of the shell than in the designs in Publications 1 and 2. But the yoke is also accordingly longer. The distance between the center p

REFERENCES:
patent: 3119324 (1964-01-01), Justus
patent: 3276102 (1966-10-01), Justus
patent: 3766620 (1973-10-01), Roerig
patent: 3889334 (1975-06-01), Justus et al.
patent: 3949455 (1976-04-01), Biondetti
patent: 3997953 (1976-12-01), Christ et al.
patent: 4213232 (1980-07-01), Biondetti

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